Spring suspension for vehicles



Dec. 30, 1941. I ,A. F.`H|CKMAN SPRING SUSPENSIN FOR VEHILES Original Fild Feb. 27, 1934 I 4 Sheets-Sheet l INVENTOR U afp- ATTORNEYS Dec. 30, 1941. A. F. HlcKMAN SPRING SUSPENSION FOR VEHICLES Original Filed Feb. 27, 1934 4 Sheets-,Sheet 2..

ATTORNEYS i A. F. HlcKMAN 1 SPRING SUSPENSION FR VEHICLES Dec. 3o, 1.941.

4 Sheets-Sheet 3 Original Filed Feb. 27, 1934 i ATTORNEYS IIIII l. %M,\\&J. L I. m. IIIUMHUm EF/Illhllm i QN E Dec. 30, 1941. MA. F. HICKMAN SPRING SUSPENSION FOR VEHICLES 4 Sheets-Sheet 4 original Filed Feb. y27, 1934 Patented Dec. 30, 1941 SPRING SUSPENSION `FOR VEHICLES Albert F. Hickman, Eden, N. Y., assignor to Hickman Pneumatic Seat Co. Inc., Eden, N. Y., a corporationl of New York Original applications February 27, 1934, Serial No. 713,161, and January 27, 1940, Serial No.

1940, Serial No. 346,968

6 Claims.

This invention relates to a spring suspension for vehicles, and more particularly to a spring suspension for vehicles or portions of vehicles subjected to a relatively small variation in load, such as in the case of passenger automobiles, aeroplanes, and the front ends of trucks and busses or for vehicles having a large load variation, as in the rear ends of commercial highway trucks.

This application is a division of my copending applications Ser. No. 713,161, filed February 27, 1934 for Vehicle spring suspension, and Ser. No. 315,985, filed January 27, 1940, for Spring suspension for vehicles, and is more Vparticularly directed to the form of the invention shown in Figs. 20, 21, and 22 of said first mentioned copending application, Ser. No. 713,161 and as also shown in Figs, 10, 11 and 12 of.said second mentioned copending application Ser.v No., 315,985, these guresbeing reproduced herein as Figs. 10, 1l and 12, respectively.

The principal objects of the invention are:v

(l) To resiliently oppose both'up and down vehicle wheel movement by a purely geometric resilient resistance instead of by an arithmetic .or a partially arithmetic .and partially geometric resilient resistance; (2) to reduce vehicle side sway any desired amount down to and including zero side sway, and even beyond to any desired amount of negative side sway; (3) to eliminate wheel tramp; (4) to considerably reduce the torsional forces to which the vehicle body is subjected, particularly as to the end of the body which is adjacent the axle being deflected; (5)

to eliminate all frictional resistance except that incident vtto pivot bearings; (6) to entirely eliminate the squeaks and lubrication inconvenience of the conventional leaf spring; (7) to definitely limit the stress to which the resilient elements may be subjected; (8) to prevent the wheels from dragging the body down when said lwheels move down beyond their normal range of movement; (9) to prevent any change of steering spindle caster even though theresilient members of the yIl, spring'suspension are stretched past their elastic limit'y or become fractured, and, at the same time, to eliminate the need of torque rods; (10) vto enable a spring suspension of this type being adjusted for maximum eiciency under dilferent loads; (11) to-considerably reduce side sway of the vehicle even if the axle pivot of the spring suspension is below the component `of the sprung weight center of gravity of the companion axle; (12) to prevent the vehicle body from being sub,- jected to lateral shocks as a consequence of lat- Divided and this application July 23,

eraLaXle movement and to thereby-also prevent tire scui; (413) to prevent any of the parts of a spring suspension of this type from becoming locked in a past-dead-center position; (14) to enable the vehicle to be safely driven even if the resilient members of the spring suspension become fractured; and (15) to provide means for enabling a considerable torsional deflection of a torsion member even though the overall length of the torsion member is relatively short. Numerous other objects of the invention and practical solutions thereof are described in detail in the herein patent specification wherein:

In the accompanying drawings:

Fig. 1 is a diminutive, top plan. of a passenger automobile chassis, provided with one form ofmy improved spring suspension.

Fig. 2 is a diminutive, vertical, longitudinal section thereof, taken on line 22, Fig. 1.

Fig. 3 is a fragmentary front end elevation thereof showing the front axle and associated parts.

Figs. 4 and 5 are fragmentary, longitudinalA sectionsthereof, taken on correspondingly numbered lines of Fig. 3.

Fig 6 is a fragmentary, vertical, longitudinal section through the rear end of the vehicle chassis, showing the rear axle and its associated parts. y

Fig. 7 is a fragmentary, vertical, transverse section thereof, taken on line 1 1, Fig. '6.

Fig. 8 is a fragmentary, vertical, transverse section thereof,` similar to Fig. 7 but taken on a line indicated by 8 8, in Fig. 6 and showing the parts in a vdifferent position from that of the other figures.

Fig. 9 is a fragmentary, horizontal section thereof, taken on line 9 9, Fig. 6.

Fig. l0 is a fragmentary, vertical, longitudinal section through the front vend of a vehicle equipped with a modified form of compound tortion rod.

Figs, 11 and 12 are enlarged, vertical, transverse sections thereof, taken on correspondingly numbered lines of Fig. 10.

It is to be understood that similar characters of reference indicate like parts in the several figures of the drawings. p

My invention may be embodied in various forms and inspring suspensions of dilferent constructions, and the present embodiments thereof are to be regarded merely as a few of the setups which carry out the invention in practice.

In the form of the invention shown in Figs. 1-9, and in all the other forms of the invention, the main frame of the vehicle chassis is constituted in the usual and well known manner of a pair of longitudinally and substantially horizontal, side frame bars and 30| which are connected at their front and rear ends repectively by the front and rear cross bars 3| and 3| l.

The entire vehicle chassis, together with its spring suspension, is constructed substantially symmetrically about a vertical longitudinal medial plane, and hence it is deemed suflicient to conne the following description almost entirely to the one (left) side of the vehicle, it' being understood that a similar and substantially sym metrical arrangement is to be found on the other (right) side of the vehicle. Furthermore, the spring suspension at the rear end of the construction of Figs. l-9 is somewhat simpler in construction than the front end, and will for that reason be described first.

Cil

Secured adjacent the rear end of the left, side,

frame bar 30 isa pair of hangers 32 and 320. In the lower end of the forward hanger 32 (see Figs. 9, 7, and 6) is journaled a pivot pin 33| having a head and a nut similar in appearance to a bolt. Said pivot pin 33|, in effect, is connected through a universal joint 3'4 with a torsion rod 33, the extreme forward end of the latter being shown as bent sharply` upward to form the torque arm 35, as shown in Figs. 4, 3, 2 and 1. The upper end of said torque arm is shown as provided with an adjusting screw 3,6

(or other suitable adjusting means), the inner end of which bears against a pad 31 which may,

if` desired, be constructed of resilient material such as rubber, and is suitably secured to the adjacent vertical longitudinal face of the companion' frame bar 30. The purpose of this adjustment screw 36 is to adjust the amount of torsional stress imposed upon its companion torsion rod 33.

It is to be understood that when such an ad- .iustment is not desired (if it be desired to render the device more fool-proof, for instance), the spring suspension may be produced with suillciently restricted torsional and other tolerances, and said adjusting screw 36 then entirely eliminated. Likewise, the pad 31 may, if desired, be

also eliminated, a resilient connection at this point being,`as. a matter of fact, of verysmall intrinsic worth due to the fact that only under very` unusual circumstances will conditions be such as to allow the torque arm to move away from the frame bar 30. that the universal joint 34 may also be eliminated if the vehicle set-up is such as to permit the two sections of the torsion rod 33 to be disposed in axial alignment with each other.

If desired, the intermediate portionspf the torsion rod 33 may, as shown, be suitably sup. ported on the frame bar 30 by a pair of bearings 38 and 33|, the latter being secured to said framebars 30, 30| in any suitable manner. l,

'Ihe rear portion or head oi the universal joint 34 is suitably flanged and detachably .connected by cap screws 40 with the inner end of a bii'urcated, front crank arm 4|. This construction, in eilect, rigidly connects the pivot pin 33| with said front crank arm 4l. It is obvious that such a rigid connection may be eil'ected in numerous ways other than in the particular manner illustrated. When the vehicle is nor-y mally loaded and at rest, this front crank arm 4I projects outwardly and substantially hori- It is likewise obvious zontally from the torsion rod 3'3, as shown in Figs. 7, 6, 9, 1 and '2. In this position the outer end of said iront crank arm 4| is resiliently urged downwardly by the resilient stress imposed upon it by the torsional stress of its companion torsion rod 33.

As best shown in Fig. 9, the outer part of said bifurcated front crank arm 4| is connected on its outer rear side b'y an integral webbing 42 (or otherwise) with the outer part of a companion, bifurcated, rearcrank arm 4|0. The inner end of this rear crank arm 4|0 is provided with a pivot pin 43 which is pivoted in the krear hanger 320 .aforedescribed. The axis of this pivot pin 43 is coincident with the axis of the pivot pin 33| thereby permitting the two crank arms 4| and 4|0 (together with the integral webbing 42 which joins them) to swing in a vertical transverse plane about the common axis of said pivot pin 33| and of said pivot pin 43.

The outer ends of both of said crank arms 4| and 4|0 are ybifurcated and are provided with a. pair of horizontal pivot pins 44 which are axially in line with each other. The central portion of each pivot pin 44 is pivoted in the normally lower end of a companion link 4.5, which latter, in the normal or static, loaded position of the vehicle spring suspension shown in Figs. 7, 6, 9 extends upwardly and inwardly from said pivot pin 44.

The upper ends of the two links 45 are split (see Fig. 7) and are clamped upon the opposite ends of a relatively long, horiaontal, longitudinal, axle-pivot shaft 46. By reason of the fact that said links 45 are both clamped at their upper ends to said axle-pivot shaft 46, the term links is not strictly accurate, but has been here used to avoid excessively clumsy phraseology and to more clearly distinguish said links from the crank arms 4|, 4|0.

Between said links 45 is disposed anl upstand- 1 ing Y shaped trunni-on 41, the upper, bifurcated arms of which are journaled on said axle-pivot shaft 46 while its lower central part or head is suitably secured by welding or otherwise to a companion Wheel spindle 48. The latter has a rear,'driving wheel 50 journaled thereon in the usual and well known manner. This spindle 46 constitutes one of the outer ends of the rear or drive axle (or axle housing) 5|.

It is admitted that, in ordinary parlance, the outer portion of an automobile drive axle is not ordinarily denominated a spindle, but it is so dened Ain Websters dictionary and it is necessary to assume some such definition as this if generic claims are to be drawn to cover the various forms of axles and wheel spindles illustrated herein. As far as the present spring suspension invention is concerned, there is no requirement that the driving axle 5| or any of the axles illustrated herein be constructed in one piece, inasmuch as each wheel spindle 48 is provided with its own individual spring suspension.. Thence it is deemed proper to' denominate each end of said drive axle 5I as a wheel spindle. v

y sistance.

part of the trunnion 41 by means of cap screws l 53 or otherwise, the outer portion of said limiting spring 52 being adapted to make contact (see Fig. 8) with the central, outer portion of the webbing 42 which forms an integral part of the two crank arms 4| land 4|0. This contact between said spring 52 and webbing 42 is initially made at a relatively long distance from the absolute dead center position and the parts then gently stopped at the final position of complete rest shown in Fig. 8 where the parts are shown as having almost, but not quite, arrived at an absolute dead-center position. `It should be noted that in this connection, however, that, even if the parts move to or even beyond an absolute deadcenter position, said parts are not likely to lock i in this past-dead-center position because the resilient force of the torsion rod 33 is always urging the pivot pins 44 downwardly, and-this factor may, in actual practice, be quite safely relied upon to breakfy any possible dead-center locking.

When the axle 5| is forced upwardly relatively to the main frame from the position of Fig. '1 (or, vice versa, when the b ody under the influence of `momentum, is forced downwardly relatively to said axle) the eiiective resilient opposing force of the torsion rod 33 increases at a geometric and not at an arithmetic rate. In this particular case, the geometric rate is of the accelerated increase type, in which increments of vertical movements of the axle are opposed by an accelerated rate of resilient ,re-v

This is primarily due to the progressive decrease in the effective lever arm of the crank arms 4|, 4|0, as they swing upwardly and inwardly about the rear section of the torsion rod 33 and the pivot pin 43 as an axis of rotation. This action is also influenced by the varying angularity of the links 45 and the fact that increments of vertical displacement of the pivot pins all cause accelerated rates of increase in the angular displacement of the torsion .rod 33. This latter is due to the fact that increments of vertical movement of said pivot pins fifi are not proportional to the accompanying increments of angular twist to which their companion torsion rod 33 is subjected.-

This geometric' action also occurs when the axle 5| moves downwardly a certain distance relatively to the frame bar 30 from the normal position of Fig. '1 to a position intermediate of the extreme position of Fig. 8. Throughout this particular movement, the geometric action is of the accelerated decrease. type, i. e., as the axle passes through increments of downward movement, the rate of decrease of the resilient force tending to push said axle downward increases.

Thus, as the axle moves downwardly from the position of Fig. '1, the resilient force tending to push it downwardly decreases at an accelerated rate. Finally, at a position intermediate of Figs. 7 Aand 8, this downward pressure on the axle 5| becomes equal to zero. Then, as said axle continues to move downwardly beyond this intermediate point, the torque arm 35 is turned or rotated outwardly away from .its pad 31, thereby relieving the torsion rod 33 of all torsional stress, thereby maintaining at zero the value of the resilient force interposed between the axle and the main frame. This conditioncontinues until the axle has moved downwardly to its lowermost pothis time, free to float along solely under the influence of gravity (plus whatever vertical momentum forces are present), this feature of the invention being of particular significance when it is realized that the load carried by the vehicle is also, at this time, solely under the influence of gravity (plus whatever vertical momentum forces are present). The consequence is that, within this particular vrange of movement, the load in the vehicle moves vertically up and down with the same acceleration and deceleration as the body and hence without changing the pressure between the load and body. Such a desirable result is quite diierent from that obtained from the conventional spring suspension in which the axle and the rest of the unsprung weight drags or jerks down the main frame whenever the strain imposed on the main springs is negative. In the present invention no such negative force, tending to pull the body downward, is possible.

The front or steering axle 5| I of the vehicle of Figs. 1-9 is provided with a spring suspension analogous to that just described for the back axle 5|. However, certain inherent characteristics of a front axle require certain modifications to the present` invention when the' same is to be applied to a. front axle. In the case of the form of front axle 5|| shown in Figs. 3, 4, 5, l and 2, for instance, a wheel spindle 48| having a wheel 50| journaled thereon is pivoted on a substantially vertical spindle pin at each end ofv said front axle 5| The two wheel spindles 48| at opposite ends of said axle are assumed to be cross connected for steering purposes in the usual and Well known manner. Extending horizontally inward from one of these spindles is a steering arm 56 connected by'a universal joint 51 with the front end of the usual steering or drag link 58 (see Fig. 5). The rear end of the latter is connected, in the usual and well known manner, by a universal joint 80 with the lower end of a manually actusition as shown in Fig. 8.v During this last menated steering lever 6 i n It is important that the steering arm 56 be never moved relatively to the axle 5|| as a consequence of any sort of up and down axle movement. Any such deleterious movement has been absolutely prevented by the construction here illustrated. A radius rod 62 is connected at its front end by a. universal joint 63 with the front axle 5|I and is connected at its rear end by a universal joint' 64 with the side frame bar 30 of the main frame. This radius rod 6.2 has its universal joint pivots 63 and 64 spaced apart the same distance as the spacing apart of theuniversal joint pivots 51 and 60 of the drag link 58. In addition to this, the disposition of the various pivot centers issuch that all planes intersecting the pivots 63 and 84 of the radius'rod 62 are parallel to all planes intersecting the pivots 51 and 68 of the drag link 58.

A small amount of longitudinal clearancel is then provided at 65 whereby the axle 5|| with its trunnion 41| is free to slide a short distance longitudinally on the axle pivot shaft 46|, the latter being iirmly clamped at its opposite ends in the upper split ends of the links 45|. Because of this arrangement, as the axle 5|| rises or falls,

it is caused to move longitudinally about the pivot 84 as a center and to thereby prevent any Cil eliminated without any serious detrimental effect on the steering of the vehicle.

There'is one very important factor involved, in any front axle set up, namely the permanence of the caster or the angle in a vertical longitudinal plane of the spindle pivots 55. 'It is to be noted that, in the present invention, the caster of the steering wheels remains absolutely xed, irrespective of whether or not a radius rod 62 is used and irrespective of whether the torsion rod 33 becomes either deformed or even completely broken.

This feature of xed caster angle is also of some importance with respect to the back axle, where it ensures the permanency of the arcs through which the universal joints of the pro-` peller shaft are caused to swing as the axle rises and falls. In the case of both front and rear axles, the construction whereby the caster angle yis permanently maintained, irrespective of what may happen to the resilient portions of the spring suspension, also ensures that all torque imposed upon the axles by the brakes is suitably taken of' any special torque care of without the need rods for this purpose.

In the case of both the front and the rear axle spring suspensions, the links 45, 45| incline downwardly and outwardly. This arrangement has two distinct advantages.

angular linkage arrangement is that it causes each end of the body of the vehicle to always tend to centralize itself relatively to the companion axle 5| centralizing tendency is caused by the effect of gravity, which may be considered a resilient, downwardly-acting force acting between the body and the roadbed and operating in a manner identical in its eiects to a metal spring connecting said distinctly understood that this; force tending to centralize each end of the body is ofa resilient nature. Because of this fact the body of the vehicle is not subjected to directly connected lateral forces movement. Such a lateral axle movement occurs, for instance, whenone end only of the axle is raised or depressed and thereby causes horizontal, lateral-movement components in all parts of the axle except at its momentary axis of rotation in those particular cases where said axis lies within the overall length of said axle. In

One effect of this body and the roadbed. It is to be as a consequence of a lateral axle i or '5|| as the case may be. Ths

angular arrangement of the links 45, 45| is that it absolutely eliminates wheel tramp. This latter may be broadly dened as a periodic vibration of either axle in a Vertical transverse plane, the denitionbeing usually limited to a rotary movement about an axis of rotation located at some pointA in the axle. In general it may be said that, if one Wheel is lifted, and if this movement causes a downward thrust on the opposite wheel, then Wheel tramp results. Such wheel tramp is prevented in the present invention by ensuring that the downward thrust of the axle pivot 45 or 46|, as the case may be, lies approximately in a plane intersecting the contact of the tire with the road. When such a condition obtains, a vertical upward thrust against one wheel is opposed by a directly opposite force passing through the axle pivot 46 or 46| and hence no downward thrust is imposed upon the opposite Wheel as occurs in the conventional spring suspension.

Another very important advantage oi the present invention is that all forces tending to twist. the frame have been Very markedly reduced as compared with conventional spring suspensions. Frame twist may be defined as a torque force applied to one end of the frame, different in direction and intensity from the torque force imposed upon the other end of the frame. In the present invention, when, for instance, one of the v'ehicle wheels is thrust upwardly, the frame hangers 32, 320 (or 32|, 32|f0) are subjected to a force intersecting the axis of the pivot pin 43 (and adjacent short end of the companion torsion rod 33). Such a force constitutes a torque force imposed upon the adjacent end of the vehicle frame, and this, all by. itself, would, of course, cause frame twist. It is to be noted, however, that, at this time, the companion torsion rod 33 is under increased stress by reason of the wheel thrust in question and hence the torque arm 35 is subjected to an increased force which also constitutes a torque force upon the vehicle t frame.' It is to be noted that this increased force the conventional spring suspension, all mcvements of the axle which are lateral with respect to the vehicle as a whole are transmitted direct- 1y4 to the body. Because of the relatively large inertia of thelatter, no appreciable lateral body movement actually occurs when such a conven tionalvehicle is traveling at high speeds and one end of the axle moves up or down. What does occur is that said body is subjected to a sharp lateral rap off/considerable force every time the axle moves /i'n any manner other than translationally. This not only seriously impairs the riding qualities of the vehicle but also subiects the body'to the succession of forces which in a short period of time loosen all the body bolts and other such fasteningsand cause the whole body to rattle.

Another important advantage obtained by the tained if the dead which is imposed upon said torque arm 35 is located at one end of the vehicle while the torque force at the pivot pin 43 is at the other end of the vehicle. Furthermore, the forces are not greatly diierent in intensity or direction. The result of this condition of aairs is that both ends of the vehicle are subjected to torque forces which do noi'I differ from each other to any marked degree in either direction or intensity, and hence frame twist is very considerably reduced. In other words, when a certain wheel of the Vehicleis forced upward, instead of twisting the one end of the vehicle frame as in the conventional spring suspension the present invention provides that the entire one side of the vehicle will be lifted a minute distance, thereby increasing the inertia resistance of the sprung weight to the resilient forces caused by the wheel movement, and very markedly decreasing frame twist and its concomitant twisting and rocking of the body and resulting loosening of the various body fittings.

As to this matterof frame twist, it is to be noted that satisfactory results can only be obend of the torsion rcd extends toward the opposite 'end of the vehicle and is positioned beyond the center of gravity of the car. If this condition does not obtain, then both ends of the torsion rod'cause torque forces which act in the same general direction and upon'the same end of the vehicle and hence cause frame twist. If, as ln the present invention, the dead" end of the torsion rod is situated beyond the ance as in the case of the conventional leaf spring.

No shock absorbers are illustrated in the form of the invention shown in Figs. 1 9. However, it is desirable to employ`shock absorbers in connection with this suspension. Nevertheless the riding qualities of a vehicle equipped with the present invention are not seriously reduced even if the shock absorbers become inoperative or are left off altogether. This is in sharp' contrast to the ordinary invidually sprung wheel suspension using helical springs, in which case the vehicle receives a terrific wrecking and `pounding if the shock absorbers become even partially inoperative. In the presentinvention,A

it has been found by definite test, that the peri- 'odic vibrations of the spring suspension are very rapidly damped out, even in the total absence of shock absorbers; As an example of how marked the dampening action is, a series of tests were run on three types of spring suspension in which the load 'and displacement were the same and also the maximum metal stress in the respective resilient members. It was found that a helical springjunderthese circumstances', would come to rest' after800 vibrations-the leaf spring after 20 vibrationsy I 5 This side sway should'be thefsame at both ends of the vehicle because otherwise'the frame' is subjected to twisting forces whenever any side sway occurs.

vOn this basis, we will now consider the. side sway at the front of the vehicle with the spring suspension in normal positionas in Fig. 3. If the front centerof-gravity component lies on the line d, there results a zeroI side sway of the frame relatively tothe axle when the vehicle is turnedto the right or left as, for instance, when rounding a corner. This is` because said line d intersects the axis of the axle pivot 46|.

This is believed by the inventor to be a correct statement, but itisadmitted that specific tests have been made to ascertain exactly where the center of gravity must be to obtain zero side sway. -Howevery assuming this relationship, as!y l stated, to be correct, then-it follows that if the center-of-gravity component is above the line d the resulting side sway will be positive as in the conventionalspring suspension. I.

If, on the other hand', the -center-of-gravity component issituated below the line d, as for instance, on line e, then the side sway is negative.- Obviously the amount of p such Inegative side sway is proportional to the 'distance between the lirios` d and e. -One important -feature of negative side sway is that, when rounding a corner, the center of gravity is shifted. toward the inside of the curve and hence lessensthe.v possibility of the car turning over. vAnother dis- I tinct advantage of negative side sway is that the and the present invention after l5 vibrations.

Why the leaf spring should be so superior to' the helical spring is easy to understand because of the relatively high friction in a leaf spring even when well lubricated. The significant fact is that in applicants spring suspension, there is no such leaf spring friction and yet its performance is four times as good as the leaf spring set-up, despite the fact that the frictionai resistance of the present invention is not materially diierent `from that of the helical spring, individually sprung wheel set up.

In the present invention, side sway of the vehicle framecan be reduced to any desired extent including zero side sway and even negative side sway. To deal rationally with this question it is highly desirable that we first mathematically split the center of gravity of the car into two components, each component lying in the intersection of a vertical, longitudinal, medial plane with vertical, transverse planes passing through the axes of the companion pair of wheels. Each component of the center of gravity is then the mass which, when the vehicle is steered to the right or left, creates a lateral force which tends to tip its companion end of the vehicle in a lateral direction relatively to the companion. The reason why it is desirable to deal with a center-ofegravity component over each axle individually is because the component over the frontxaxle is usually at a different height above the ground from the center-of-gravity component over the rear axle and hence requires a different arrangement to ob- Vtain the same kind and vdegree of side sway.

n'- In) tendency of the person or goods in the vehicle to move sidewise under the inuence of centrifugal force is lessened. This is` because the supporting surface is tilted when the side sway occurs and hence `one component of the side,A sway force is directed perpendicularly downward against said supportingsurface.' Negative side sway has the further advantage of beingmuch superior as to its psychological reaction on' the persons riding in the vehicle as compared with zero-or' positive side sway, not only because of the decrease in the force tending to moveI the persons sidewise in their seats, but also because there is a natural tendency for/a person to lean inward or.bank) on'acurve. 'This psychologicai-.effect is probably ychieiiy due to the instinctive feeling of greater safety which is obtained when the center of gravity is shifted toward the inside of the curve along which the person is moving.

It is obvious that the amount of side sway varies with the position of the axle pivots relatively to the vehicle frame. When it is desired to keep the maximum possible side sway under any certain definite amount, this may be effected by either positioning the axle pivot high enough above the axle to accomplish this result, or by suitably lowering the center of gravity of the body. It isto be noted in this connection, however, that the factors affecting side sway change very considerably when the frame and Aaxle are approximately in the extreme position of Fig. 8. This is due to the fact that, when the parts are approximately'in `this position, any outward centrifugal movement of the inner part of the vehicle frame, tends to cause the pivotsl 43, 44 and 46 to all lie in one straight line, .and such a dead centerf tendency is resisted by forces which rapidly approach infinity 1 as said pivots approach a straight line rela- 'tionship. It should be borne in mind, however,

that any such condition as that shown in Fig. `8

would be exceeding rare in actual practice, particularly when the vehicle is equipped with shock absorbers Whose chief function is to restrain upward movements of the body relatively to the axle.

It has also been found in the present invention from actual practice and from analysis `based on said practice that side sway has been rendered mathematically more negative in amount by reason of the angularity of the links 45 which normally slope down and out from the axle pivots 46|. Because of this angularity, when the body shifts laterally in rounding a curve, the outer part of the body is elevated and the inner part allowed to fall, relatively to the axles. Such a tilting is equivalent in its effect to lowering the center of gravity of the body or elevating the axle pivots 46|, either of these changes rendering side sway more negative.

It is desirable that when a vehicle is at rest and is carrying whatever load it is intended to carry, the parts be approximately in the normal position of Fig. 7. This is because: (A) In this position the smallest initial pressure increments cause the maximum upward axle movement; (B) The total upward axle movement is large enough to properly cushion" the heaviest upward forces; and .(C) The axle can move a considerable amount downward before it reaches the extreme position of Fig. 8. With the construction thus far described, this result cannot be attained if the live load varies considerably in amount as, for instance, in the case of the rear axle of a truck. y

Under such circumstances the construction forming the subject of this divisional application and illustrated in Figs. 10-12 may be adopted. Inthis case the primary torsion member or torsion rod 338 functions precisely as in the other constructions described, being connected at one end with a crank arm 4|8 'and provided at its other end with a torque arm 358, thus imposing a certain definite resilient torque force upon said torque arm 358. This torque force is suicient to provide suitable riding qualities to the back axle when the truck is entirely unloaded or less than half loaded.

When the truck is completely loaded or more than half loaded, an auxiliary torque force is adapted to be imposed upon the crank arm 4|8. 'Ihis is eifected by a. torsion tube 20 which is suitably journaled on the frame at Opposite ends at |2| and |22. The bore of said torsion tube is provided with the bushings |23 and |24 in which aforesaid torsion rod 338 is journaled. The live (right) end of the torsion rod 338 is provided with anY annular collar |25 having a pressure lugl26 projecting inwardly from one side of its bore. Secured by welding or other- `Wise to the adjacent end of the torsion tube |20 is a head |21 having a pressure tongue |28 projecting laterally therefrom and adapted to engage with aforesaid pressure lug |26. Secured by welding or otherwise' to the dead (left) end of said torsion tube |20 is a large sprocket wheel |30 engaged upon its periphery by a belt chain |3|. 'I'he latter at its inner portion engages with the peripheryof a4 small sprocket wheel |32 secured to one end of a shaft |33. Said shaft is suitably journaled on a bracket |34 secured by a cap screw |35or otherwise to the frame 308. f

Also secured to said shaft |33 is a ratchet wheel |36, the peripheral ratchet teeth of which are adapted to be-engaged by a ratchet dog |31 pivoted to the bracket |34 upon a pivot pin |38. A past-dead-center tension spring |40 is connected at |4| to said bracket |34 and at |42 to the ratchet dog |31 and is adapted to either resiliently hold said ratchet dog in or out of engagement with the teeth of the ratchet wheel |36 by reason of the geometric position of the pastdead-center spring connections |4| and |42 relatively to the ratchet dog pivot |38. Said ratchet dog |31 is adapted to be manually thrown either into or out of engagement with said ratchet wheel |36 by a throw lever |43 which is secured to the outboard end of the pivot pin |38.

Secured to the outboard end of the shaft |33 is a crank lever |44 which permits of the convenient manual rotation of said shaft and, through the belt chain |3|, of the dead end of torsion tube |20. The amount of torsion which can be imposed upon said torsion tube is definitely limited by a stop pin |45 which is se,- cured to the large sprocket wheel |30 and is adapted to come into engagement with the lower face of a stop arm |46 secured by the cap screw |35 to the` frame 308. In a similar manner, the extent to which vsaid torsion tube |20" can be manually rotated in a negative vdirection by the crank lever |44 is limited by a limiting pin |41 also secured to said. large sprocket wheel |30 and adapted to come into contact with the upper face o'f said stop arm |46.

When the truck has been loaded to more than half of its total live load capacity, the operator is enabled, if vhe wishes to improve the vriding quality of the rear end of said truck, to impose a torsional strain upon the torsion tube |20 by first throwing the ratchet dog |31 to the operating position shown in Fig. 11 and then rotating the crank lever |44 in a counterclockwise direction (as seen in said Fig. 11). If the operator wishes to impose a maximum torsional stress upon the torsion tube |20, he continues this rotation until the stop pin |45 comes into contact with the stop arm |46, as shown in Fig.

'11. Under such conditions the crank arm 4|8 is subjected to the torsional stress of both said torsion tube |20 and also the torsin rod 338. When a sufficient negative movement of said crank arm 4|8 occurs (dropping of the axle to or near the position of Fig. 8) any possibility of imposing a negative stress in the torsion rod 338, and thereby jerking down the vehicle frame is prevented by the torque arm 358 moving away from the frame 308. Similarly, when a suiiicient downward axle movement occurs, the pressure lug |26 connected with the crank arm 4| 8 moves* out of contact with the pressure tongue |28- of the torsion tube 20, thereby preventing said torsion tube from ever jerking down the vehiclebody.

I claim as my invention:

1. A .vehicle spring suspension comprising: a frame; a spindle having a Wheel journaled thereon; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer part of said crank arm with said spindle; a torsion rod connected atv one end to said frame and exgaging means and said auxiliary resilient means to vary the eiect of said auxiliary resilient means.

2. A vehicle spring suspension comprising: a frame; a spindle having-a wheel journaled thereon; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer` part of said crank arm with said spindle; a torsion rod connected at one end to said frame and extending longitudinally of said frame and connected at its opposite end to said crank arm to resist rotation of said crank arm; a torsion tube surrounding a part of said torsion rod;

means carried by the live end of said torsion rodadjacent said crank arm and the adjacent end of said torsion tube and arranged to interengage following a predetermined. stress on said torsion rod thereby to distribute a greater stress between said torsion rod and torsion tube; means for securing the opposite end of said torsion tube to said frame and means for adjustably altering the relation between said engaging means and saidv auxiliary resilient means to vary the eiect of said auxiliary resilient means.

3. A vehicle spring suspension comprising: a

frame; a spindle having a wheel journaled thereon; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer part `of said crank arm with said spindle; a torsion rod connected at one end to said frame and extending longitudinally of said frame and connected at its opposite end to said crank arm to resist rotation of said crank arm; a torsion tube surrounding a part of said torsion rod; means carried by the live end of said torsion rod adjafr:

cent said crank arm and the adjacent end of said torsion tube and arranged to interengage following a predetermined stress on said torsion rod thereby to distribute a greater stress between said torsion rod and torsion tube; and means for ad- V justably securing the opposite end of said torsion tube to said frame comprising a sprocket wheel fast to sai'd opposite end of said torsion tube, a second sprocket wheel, a belt chain operatively engaging the peripheries of said'sprocket wheels, means for sprocket'wheel on said frame and means for adjustably rotating said second sprocket wheel.

4. A Vehicle spring suspension comprising: a

-frame; a spindlehaving a wheel journaled therei on; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer part of said crank arm with said spindle; a torsion rod connected at one end to said frame and extending longitudinally of said frame and connected at its opposite end to said crank arm to resist rotation of said crank arm; a torsion tube surrounding a part of said torsion rod; means carried by the live end of -said torsion rod. adjacent said crank arm andthe adjacent end o f said torsion tube andarranged Ito interengage following a predetermined stress on said torsion rod thereby to distribute a greater stress between said torsion rod and torsion tube and means for adjustably securing the opposite end of said torsion tube to said frame comprising a large sprocket Wheel fast to .said opposite end of said torsion tube, a small sprocket wheel, a belt chain supporting said second on; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer part of said crank arm with said spindle; a torsion rod connected at one end to said frameand extending longitudinally of said frame andv conresist rotation of said crank arm; a torsion tube f surrounding a part of said torsion rod; means carried by the live end of said torsion rod adjacent said crank arm andthe adjacent end of saidwtorsion tube and arranged' to interengage following a predetermined stress on said torsion rod thereby to distribute a greater stress between said torsion rod and torsion tube comprising an annular collar mounted on said live end of said torsion rod, a pressure lug projecting inwardly from said annular collar, a head mounted on said adjacent'end of said torsion tube and a pressure tongue projecting laterally from said head and adapted to engage with said pressure lug; and means for adjustably securing the opposite end of said torsion tube to said frame comprising a sprocket wheel fast to said opposite end of said torsion tube, a second sprocket wheel, a belt chain operatively engaging the peripheries of said sprocket wheels, means for supporting said second sprocket wheel on said frame and means for adjustably rotating said. second sprocket wheel. l i

6. A vehicle spring suspension comprising: a frame; a spindle having a wheeljournaled thereon; a crank arm pivoted longitudinally on said frame; means pivotally connecting the outer part of said crank arm with said spindle;` a torsion rod connected at one end to said frame and extending longitudinally of said frame and-connected at its opposite end to said crank arm to resist rotation of said crank arm; a torsion tube c said annular collar, a head mounted on said adjacent end of said torsion tube. and a pressure tongue projecting laterally from said head and adapted to engage with said pressure lug; and

means for adjustably securing the opposite end of said torsion tube to said frame comprising a large sprocket wheel fast to said opposite endof said torsion tube, a small sprocket wheel, a belt chain operatively engaging the peripheries of said sprocket wheels, means for supporting said small sprocket wheel on said frame and manu- 'ally operable means for adjustably rotating said small sprocket wheel. ALBERT F. HICKMAN.

nected at its opposite end to said crank arm to 

